Two week checkpoint - managing air quality

Hello everyone, this is my first time growing anything. After months of research - I soaked some seeds. That was 16 days back. I’ve since almost killed my plants 3 times. They’ve been stable for the last 3-4 days now. I’m debating if they’re ready for fimming.

My main concerns are the height of the plant. I was expecting faster growth. And also the strength of the main stem. The plants tend to keel over if the clay pebbles are moved. But I’m thinking this might be normal? I do have a fan in the tent for circulation. The strain of this plant is Moby Dick.

I’ve been monitoring my grow and here are my Day/Night values:

temperature: 85-90/75-85
humidity: 65-70/55-60
CO2: 400-900 ppm (my unit does not measure values under 400 ppm - and it is at that level often)

I’ve been pumping fresh air into my tent only a few times a day - and notice that the CO2 levels drop quickly when the tent is shut. I realize that the plants are probably lacking oxygen as well.

The problem is that every time I pump fresh air into my tent - it drops the humidity level. And if I add a CO2 system to my setup - I’m expecting a drop there as well. So I’m hoping for some tips on how to add fresh air to my tent.

Is it better to:
a: Pump in fresh air only once every 60 minutes
b: Not worry about humidity dropping to 45%, slightly lower temps, and natural CO2. So pump in lots of fresh air.

I’m thinking this must be a common problem - and would appreciate any pointers.

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My closet grow is similar, and while I had no temp problems the humidity was low. I got a $20 humidifier on Amazon, and set it by the intake vent. Fresh air is important, especially with your high temps. I would sacrifice humidity to get the temp lower though.

Little/no air exchange + high temp + high humidity = mold.

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Whoa! I had not realized I was creating a perfect environment for mold. Thanks for pointing it out. Will install an intake fan immediately.

Also thinking of adding a drop of essential oils to the humidifier (like clove, or tea tree oil) to avoid problems like mold and other airborne pathogens.

I have no intake fan. I have good exhaust fan. All you need to do is allow air in for the exhaust to exchange. Just remember that if smell is a concern you need the exhaust running 24/7, and your inlet needs to be small enough that there is a slight negative pressure in the tent.

Like, if you have a fan sucking 100cfm of air out, it has to come from somewhere. Just make sure that the vent doesn’t allow the free exchange of air both ways. Cut a two foot hole in the tent, the exhaust means nothing. Cut s 1/2" hole in the tent and you create a mini-cyclone :wink:

You can use window screen and duct-tape and kill it.

Gotcha! Your post made me realize 2 problems with my tent.

It has a tower fan for plant exercise - which is creating a tornado effect. Thought this was good - but I realize it will also vent humidity and co2 quickly. will replace this with 2 traditional fans.

There is a 450 cfm fan setup as an intake - for which I was going to get a speed controller. But this seems like a bad idea now - especially since none of the controllers are ETL certified.

I have a 3x3x7 tent - so I’ll setup this fan as an exhaust and add a charcoal filter later -

Appreciate your input!

Glad to be of help. If I could give one pointer, it would be to stop thinking “weed”. If a plant wants an environment that is about what I find comfortable, would I want to be in that tent (closet, whatever). A guy was asking about building a bunker for an underground northern-climate grow. Sometimes it’s best to think about what you could tolerate, and go from there.

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good one @whodat66! I sometimes have to remind myself that it’s really all about having fun and learning!

My expectation is about $2k in seutp costs (including about $500 in mistakes) and maybe 2 failed attempts. I’d like to make most of my mistakes as early as possible - so I lose less time. That’s why I’m taking all the risks now!

The goal is to setup a smart system (wifi/bluetooth) - that can be mostly autonomous - with phone alerts when things are not going as expected.

So far I’m very happy with my tent, lights, and aeroponic setup. I’m seeing my temp, humidity, and co2 on my phone already. This screenshot below - indicating a drop in humidity - lets me know that my humidifier is probably out of water.

I still have a long checklist of things I want to improve! And I’m thankful for having found a community of growers!

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I have had great luck with a cheap-o humidifier just outside my closet, by the intake vent. Brought the rH from about 45% to 65%, and the temp down 4 degrees. I let it run dry yesterday and the temp shot right up.

I cleaned the insulation out of the bottom of that stud-space, an the vent inside the closet is higher to help with light.
I’ve been able to lower my lights to a normal distance with the temp controlled.

But my electric bill isn’t bad, so if I have to I can always turn down the thermostat and put on sweats LOL

@HankSD I have that fan and it works well, but I would suggest the 6 inch since heat is an issue. Like I said the 4in works but I wish I had gotten the 6in, if it is too much you can always turn it down. Plus the controller will run 2 fans, 2 4in? I have just the one and no intake fan, just fresh air hole w/ filter and it works fine as @Whodat66 said. Keep on it man and you will figure it out. Humidity can ruin it all though…

That’s interesting @whodat66. Placing the humidifier outside hadn’t occurred to me. I’m going to try it and see if it will help me better control the humidity.

@holmes - Already ordered the 4 in. Should be receiving it today. Let’s see. There’s room for 2 fans - but I’d rather have one. I’ll upgrade to the 6 if necessary.

Thanks for the tips!

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I got a 4" in-line fan from Amazon. Beware the ‘dust-cover’ that comes with the carbon filter if you get one. It restricts airflow like mad.

Here is my ‘pre-plant’ set-up I took it apart to put the cloth pre-filter over the canister (I have a brace on the end) and ended up just sliding it off to get more airflow.

If I had it to do over, I would go with the largest fan I can fit. You can always dial it back with a rheostat, but you can’t turbo-charge it to get more cfm…

This one may transfer to a veg-room when I harvest.